You remember why, I assume. They were among the least accurate in 2012. It was a huge and hugely humiliating fail.
https://www.politico.com/story/2015/10/gallup-poll-2016-pollsters-214493
They can package it as focusing more on issues than on horse races, but yes your point is more likely on target as to why issues over horse races:
There’s no means on an item like this to give them a grade, to know how accurate or inaccurate they are, like there is in election. They cannot fail anymore.